This Phase I STTR addresses the significance of changes in the serum levels of prostate specific antigen (PSA) in prostate diseases and also intends to develop and determine the sensitivity and specificity of a new PSA assay (NPSAA) that is expected to help distinguish between prostate diseases (with emphasis on distinguishing between benign prostatic hyperplasia (BPH) and prostate cancer). A battery of monoclonal antibodies (MAbs) capable of distinguishing the free form of human PSA from the complex formed between PSA and a plasma protease inhibitor, a-l-antichymotrypsin (ACT) have been developed and will be utilized for studies proposed. It is expected that the NPSAA kit to be developed will be particularly useful in distinguishing prostate cancer from BPH when the serum PSA concentration is slightly above normal, in the range of 4-10 ng/ml; in this range, the conventional methods for measuring PSA levels are not useful for determinations of the type of prostate disease present. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE